What the purpose of putting radio active metals in tubes or electronics?

Quote from: GlennSprigg on August 31, 2019, 12:55:48 pm

Basically, 'Thoriated' Tungsten vastly improved the Electron Emissions from Cathodes. (A given ).
However, for the supporters of Conventional Current flow, I guess it vastly improved the ABSORPTION
of electrons, or did something 'magical' to the Positrons that REALLY flowed from the Anode...   

I thought this was due to properties of thorium which do not rely on radioactivity and more with emissivity, so a unhappy match by physics to a nasty metal (obviously you are in deep shit with mother nature if you need to use radioactive materials in a god damn radio amplifier)

https://en.wikipedia.org/wiki/Hot_cathode#Thoriated_filaments

they are also used in old coleman lanterns (but I think now they use some kind of cerium ). It seems to require a plasma to function in a lantern, you will not get the brightness from electrically heating it, as I learned from this forum to my displeasure (complicated physics). It is not just a heat to light converter that functions in the presence of a plasma either, I think it needs to have 'flow' and some how depletes it.

https://en.wikipedia.org/wiki/Candoluminescence

It's probably some how related to the electrical effect? (maybe why they thought to try to use it)

The characteristics of thorium  that are used in these applications are not primarily to do with their radioactivity, as there are other materials which have similar properties, but have little or no radioactive content.
Thorium was used, because it works better-- that's all.

Indirectly heated tubes may or may not use thorium oxide in their "oxide coated cathodes" (most likely, not!).
In any case, the quantity is miniscule---- the probability  of damage from the radiation from such cathodes is vanishingly small from listening to a tube radio.

Large transmitting tubes use "thoriated tungsten", where the filament material is an alloy of thorium &  tungsten.
By a mechanism described in the Wiki you linked previously, the thorium component becomes concentrated at the surface, improving the ability of the filiament to emit electrons.

Obviously, these are larger elements, so there would be more possibility of radiation.
Most high powered Transmitting tubes have an external anode, which makes up most of the structure of the tube.
Any radiation has to make its way through these massive structures, then through the metal of the transmitter cabinet  & so on.

We need a "reality check" when we start worrying about peripheral radiation sources like this.

People work daily with such delights as Cyanide, which  has a "half life of infinity"-------it will always be just as poisonous as it is now!
Another thing is Phosphoric Acid --- a lot will burn you alive, a little bit is great for  killing rust.

We used to make teeth fillings with Mercury amalgam ----How many people died from that?

People used coal fires to get warm for many years---burning coal releases radioactve products, to say nothing of the several kW of Electromagnetic radiation  in the form of heat!

The characteristics of thorium that are used in these applications are not primarily to do with their radioactivity, as there are other materials which have similar properties, but have little or no radioactive content.Thorium was used, because it works better-- that's all.Indirectly heated tubes may or may not use thorium oxide in their "oxide coated cathodes" (most likely, not!).In any case, the quantity is miniscule---- the probability of damage from the radiation from such cathodes is vanishingly small from listening to a tube radio.Large transmitting tubes use "thoriated tungsten", where the filament material is an alloy of thorium & tungsten.By a mechanism described in the Wiki you linked previously, the thorium component becomes concentrated at the surface, improving the ability of the filiament to emit electrons.Obviously, these are larger elements, so there would be more possibility of radiation.Most high powered Transmitting tubes have an external anode, which makes up most of the structure of the tube.Any radiation has to make its way through these massive structures, then through the metal of the transmitter cabinet & so on.We need a "reality check" when we start worrying about peripheral radiation sources like this.People work daily with such delights as Cyanide, which has a "half life of infinity"-------it will always be just as poisonous as it is now!Another thing is Phosphoric Acid --- a lot will burn you alive, a little bit is great for killing rust.We used to make teeth fillings with Mercury amalgam ----How many people died from that?People used coal fires to get warm for many years---burning coal releases radioactve products, to say nothing of the several kW of Electromagnetic radiation in the form of heat!